A conventional ingredient in the magnetic coating on magnetic recording tapes or discs is finely particulate aluminum oxide, for the purpose of reducing mechanical wear of the tape and keeping the magnetic recording and/or reading heads of the recording or playing device clean by its abrasive action. U.S. Pat. No. 3,630,910 discloses coatings containing abrasive powders, and U.S. Pat. No. 3,007,807 discloses the use of inert powders such as diatomaceous earth (silica) to disperse the magnetic particles. Coatings containing alumina may also be used in the disc contacting surface of the holder for rotating disc type magnetic recordings.